Living near a river has many advantages, but it also exposes people and properties to certain risks. One of the risks is getting hit by floods, which can cause damage to life and property. The adverse effects of floods vary widely, from minor inconvenience of road-side puddles to loss of life.
Managing flood risk starts by identifying the areas of land adjacent to stream and rivers that are flood-prone at various frequencies (or with different return periods).
In the Rideau Valley, planning and development approval policies prohibit or carefully control new development in areas that are expected to be flooded during a 1:100 year flood, or more frequent floods. The 1:100 year flood has a 1% chance each year of being equaled or exceeded.
The flood risk mapping is used in the RVCA regulations work and in the municipal land use planning process to ensure that new development does not add to the risk of flood damages or public safety risks associated with flooding. The mapping is also used in the flood forecasting and warning program to identify the areas that can be expected to have problems when flood events occur. The mapping is an essential starting point for the planning of flood protection works.
Flood plain mapping has been produced for more significant developed areas of the Rideau watershed where there is a recognized potential for flood damages.
In this section, you can view the available flood risk maps for the Rideau River Watershed.
In general, flood plain mapping is a four step process involving the application of modern tools and analytical methods in computer-based topographic mapping and hydrology and open channel hydraulics.
Step 1 – preparation of accurate topographic mapping of the river and the adjacent lands
Step 2 – calculation of the expected river flow (or discharge) for different return periods (or flood frequencies) by using statistical hydrology methods, if there are sufficient records of historical streamflow, or using mathematical hydrologic models, or both
Step 3 – calculation of expected water levels along the river for the expected discharges, using mathematical models that simulate the hydraulic characteristics of the river and its flood plain
Step 4 – plotting flood lines on the mapping to illustrate the areas that are expected to be inundated
The required studies are undertaken by qualified professionals, to technical standards that are prescribed by the Ministry of Natural Resources.
Within the Rideau Watershed, several floodplain mapping projects have been conducted during the last three decades. Digital versions of the more recent floodplain mapping studies are available below; while for the older reports, a reference list is provided below. All flood map sheets (from the studies listed below) are available in hardcopy or in digital format from RVCA – Please send requests to Ferdous Ahmed at email@example.com at (613) 692-3571 ext. 1170.